Why East Valley Pools Turn Green in Summer, and What a Turn Around Involves

Nobody plans for a green pool. You leave for a long weekend with the water clear, you come back on Monday, and the pool looks like pea soup. Owners in Chandler, Gilbert, Mesa, Tempe and Phoenix call us about this more than almost anything else in summer, and the cause is almost never a mystery once you know where to look.

What the green actually is

That color is algae, a living thing, and it multiplies the way any plant does when it has light, warmth and food. Free-floating algae is what turns the whole body of water green. A small number of spores arrive on the wind every day, and healthy water with a steady sanitizer level stops them before they get started. Green water means the sanitizer lost the race.

Why the East Valley tips the balance so easily

Start with the heat. When afternoons sit at 110 degrees, pool water gets warm enough to feel like a bath, and warm water is where algae thrives. Sunlight also breaks down chlorine fast, so the sanitizer you added Saturday can be mostly gone by Tuesday. An unprotected pool simply burns through it.

Then add what falls into the water. Monsoon storms push dust, leaves and grit across the valley in one afternoon, and a single storm can drop a season of palo verde litter into a pool. That material is food for algae, and a sudden load of it can overwhelm a sanitizer level that was fine the day before.

Finally, circulation. A pump that stops for a day, a timer that gets knocked off, a filter that's too dirty to pass water, or a tripped breaker after a storm all leave the water sitting still. Still water in July is an invitation. A pool that runs well can fall behind in two or three days when any one of these goes wrong, and several of them often happen together.

The common ways it happens

• A stretch of missed service while the owner is traveling
• A storm that dumps debris and knocks out power to the pump
• A filter that's clogged and no longer moving enough water
• Low sanitizer after a few brutal heat days in a row
• A pool left uncovered and unmaintained after a house changes hands

What a green pool turn around involves

A green pool turn around is the job of bringing a green pool back to clear, swimmable water. It's different from routine upkeep, because the work starts with a pool that's already lost. In general terms, it runs in a few stages.

First, the heavy material comes out. Leaves, silt and anything sitting on the floor get removed so the treatment isn't wasted on feeding the problem. The walls, steps and benches are brushed to knock algae loose from every surface, not only the water.

Second, the water is tested, and the chemistry is corrected so a strong sanitizing treatment can actually work. Pool water that's badly out of balance fights the treatment. Third, the sanitizer is raised well above normal levels to kill what's in the water. This is general craft, and the exact amounts depend on the pool, the water and the condition it's in.

Fourth, the filter runs hard. Dead algae doesn't disappear. It gets caught by the filter, which means the filter fills up quickly and needs repeated attention, whether that means cleaning a cartridge or back washing a sand filter. This is the stage owners underestimate. A clean-looking pool can still be full of dead material that has to be pulled out before the water turns truly clear.

How long it takes, and what to expect

It's rarely finished in a single visit. A lightly green pool can clear in a few days, while one that has been sitting for weeks takes more work and more filter cleanings. Water may go from green to cloudy to clear along the way, and cloudy is a sign of progress. You also shouldn't swim until the water has been tested and is clear, since green water hides what's on the bottom.

Keeping it from coming back

Once the pool is clear, the best protection is regular service. A weekly visit with brushing, testing and a look at the equipment is the thing that stops the next green weekend. Weekly service starts at $90 per month, and the details are on the weekly pool service page.

If your pool is green right now, Del Sol Pool Service & Repair can help. We're family owned and operated, fully licensed, bonded and insured, ROC#275375. Read about green pool turn arounds, then send the office a note or call (480) 272-7260, Monday through Friday, 8am to 5pm.